Employee Benefit Plans - MEC - Contributions and Benefit Payments (Details) $ in Millions	Dec. 31, 2017 USD ($)
Pension Plan [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 8
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	60
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	61
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	60
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	59
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	57
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	256
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	3
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	54
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	55
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	57
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	55
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	54
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	243
Other Postretirement Benefits Plan [Member] | MidAmerican Energy Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	1
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	19
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	20
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	21
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	22
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	21
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 98